Okie dokie, so long story short, I was the brother of the bride and IN the wedding party. This made it very hard to photo during the wedding. Being father of the groom means that you'll need to be in a LOT of photos. So here's how I would do it. Bring your 1DX, your 2 600EXs, 2 shoot through umbrellas, a ST-E3 commander for the 600EXs, 2 lightweight light stands that you can move, a 35L, and an 85L. That's all you'll actually need in terms of gear. While I don't recommend you try and shoot bits of the wedding yourself since it will kinda drive you insane, if you're the last line of defense in getting some quality photos, I would just say that you should be in the action and shoot sporadically while also being a part of the wedding. The 2 shoot through umbrellas will provide soft light when it gets darker and you can use those for a couple shots with your kids so that they are decently lit. During reception, I suggest bouncing on camera flash or set up the light stands in a triangle pattern with your camera and have no umbrellas. Try to be discreet when shooting and most important of all is to enjoy the wedding. Also on a separate note, if you have too many drinks during the wedding, your photography skill does not go up with the number of drinks you have had.